Intracellular pathway of 125i somatostatin (∗ s14) in isolated guinea pig pancreatic acini : quantitative autoradiography in electron microscopy

Isolated guinea pig pancreatic acini were specifically depleted of glutathione by treatment with 2-cyclohexene-1-one (2-CHX-1). Untreated acini contained 4.3 +/- 0.6 micrograms of glutathione per milligram protein. Incubation with 1 mM 2-CHX-1 for 5 min at 37 degrees C depleted glutathione to 17% of control values; 5 mM 2-CHX-1 depleted glutathione to less than 4% of control values. Incubation with 2-CHX-1 also impaired the ability of the isolated acini to secrete amylase in response to stimulation with carbachol and the ionophore A23187. The depletion of glutathione and the inhibition of amylase secretion by 2-CHX-1 were both dose dependent and time dependent. Incubation of acini with 2 mM 2-CHX-1 for 15 min at 37 degrees C reduced glutathione levels to 6.6% of control and reduced carbachol-stimulated amylase release to 63% of control. Higher doses of 2-CHX-1 or longer incubations resulted in greater depletion of glutathione and greater inhibition of carbachol-induced amylase release. These data indicate that specific depletion of glutathione impairs the ability of isolated acini to secrete amylase in response to physiological and pharmacologic stimuli and suggest that glutathione has a role in stimulus-secretion coupling in the exocrine pancreas.

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Immunocytochemical localization of histamine in secretory granules of rat peritoneal mast cells with conventional or rapid microwave fixation and an ultrastructural post-embedding immunogold technique.

Journal of Histochemistry & Cytochemistry ◽

10.1177/40.9.1506663 ◽

1992 ◽

Vol 40 (9) ◽

pp. 1247-1256 ◽

Cited By ~ 21

Author(s):

G R Login ◽

S J Galli ◽

A M Dvorak

Keyword(s):

Electron Microscopy ◽

Mast Cells ◽

Guinea Pig ◽

Secretory Granules ◽

Fixation Method ◽

Structural Localization ◽

Thin Sections ◽

Aldehyde Fixation ◽

Peritoneal Mast Cells ◽

Rat Peritoneal Mast Cells

We used a post-embedding immunogold labeling approach to define the fine-structural localization of histamine in rat peritoneal mast cells that were fixed using either standard aldehyde fixation or a fast microwave-aldehyde fixation method. Specimens were processed routinely for electron microscopy. Thin sections were exposed first to guinea pig antihistamine antiserum and then to gold-conjugated goat IgG directed against guinea pig IgG. By transmission electron microscopy, gold particles were localized to the matrix of cytoplasmic granules. Control sections treated with non-immune sera did not show labeling of mast cells. Adsorption of antihistamine antiserum with purified histamine or histamine bound to agarose showed a significant reduction (p less than 0.005) in granule staining. We also confirmed that our isolation procedures yielded functionally competent mast cells which released histamine when stimulated with sheep anti-rat IgE antiserum or with compound 48/80. These studies define the conditions of fixation for electron microscopy that are appropriate for the localization of histamine in the granule matrix of rat peritoneal mast cells.

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Regulation of bombesin receptors on pancreatic acini by cholecystokinin

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1989.256.2.g291 ◽

1989 ◽

Vol 256 (2) ◽

pp. G291-G298

Author(s):

M. Younes ◽

S. A. Wank ◽

R. Vinayek ◽

R. T. Jensen ◽

J. D. Gardner

Keyword(s):

Guinea Pig ◽

Response Curve ◽

Binding Capacity ◽

The Other ◽

Single Class ◽

Pancreatic Acini ◽

Cck Receptors ◽

Cyclic Monophosphate ◽

High Affinity ◽

Bombesin Receptors

When guinea pig pancreatic acini are first incubated with the COOH-terminal octapeptide of cholecystokinin (CCK-8), washed, and then reincubated with 125I-[Tyr4]bombesin (125I-[Tyr4]BN) there is a significant decrease in binding of 125I-[Tyr4]BN compared with that observed with pancreatic acini that have been first incubated with no additions. The CCK-8-induced decrease in binding is maximal after 90 min of first incubation is abolished by reducing the temperature of the first incubation from 37 to 4 degrees C or by adding L364,718 to the first incubation and cannot be reproduced by first incubating acini with A23187, 8-bromoadenosine 3',5'-cyclic monophosphate (8Br-cAMP), 8-bromoadenosine 3',5'-cyclic monophosphate (8Br-cGMP), or 12-O-tetradecanoylphorbol 13-acetate. 125I-[Tyr4]BN interacts with a single class of receptors on pancreatic acini, and first incubating acini with CCK-8 decreases the affinity of BN receptors for BN with no change in the maximal binding capacity. CCK-8 does not alter the rate at which bound 125I-[Tyr4]BN dissociates from pancreatic acini; therefore, CCK-8 must alter the rate at which the radiolabeled BN analogue associates with its receptor. Pancreatic acini possess two classes of CCK receptors: one has a high affinity for CCK-8; the other has a low affinity for CCK-8. The dose-response curve for CCK-8-induced inhibition of binding of 125I-[Tyr4]BN appears to to reflect occupation of low-affinity CCK receptors by CCK-8.(ABSTRACT TRUNCATED AT 250 WORDS)

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Somatostatin inhibits VIP-stimulated amylase release from perifused guinea pig pancreatic acini

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1988.254.2.g217 ◽

1988 ◽

Vol 254 (2) ◽

pp. G217-G223 ◽

Cited By ~ 2

Author(s):

P. Singh ◽

I. Asada ◽

A. Owlia ◽

T. J. Collins ◽

J. C. Thompson

Keyword(s):

Guinea Pig ◽

Fold Increase ◽

Optimal Conditions ◽

Amylase Release ◽

Pancreatic Acini ◽

In Vitro System ◽

Basal Release ◽

Perifusion System ◽

Chamber Size

We have examined the direct effect of somatostatin (SRIF) on basal and stimulated amylase release from guinea pig pancreatic acini using the in vitro method of continuous perifusion. The optimal conditions of flow rate, chamber size, acinar cell volume per chamber, and period of secretagogue infusion were defined for the perifusion system. The kinetic profile of amylase release in response to cholecystokinin-octapeptide (CCK-8), vasoactive intestinal peptide (VIP), and SRIF was studied. Under optimal conditions, the acini were found to remain equally responsive to an ED50 dose of CCK-8 (0.5-0.8 nM) for 12 h of perifusion. The duration of amylase response to any given dose of CCK-8, given for the optimal period of 5 min, was 80-100 min. The total amylase released minus the basal release divided by 90 min (delta response) in response to the maximum effective (Maxeff) dose of CCK-8 (100 nM) was 14,667 +/- 1,433 U/l (amounting to a 10-fold increase compared with basal values). When compared with the amount of total delta amylase released in response to the Maxeff dose of CCK, the total amylase released in response to the Maxeff doses of SRIF (1 microM) and VIP (10 nM) was 10-21% and 51-59%, respectively. SRIF (100 nM) significantly decreased VIP- (0.1-1.0 nM) stimulated amylase release by 45-70% in the perifusion method of study but had no significant effect on the CCK-stimulated amylase release. This suggests that the perifusion method can be used for investigating the mechanism of SRIF-mediated inhibition of VIP effects on amylase release in an in vitro system.

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Discovery of a cholecystokinin analogue with partial agonist activity

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1984.247.3.g261 ◽

1984 ◽

Vol 247 (3) ◽

pp. G261-G264 ◽

Cited By ~ 1

Author(s):

J. M. Howard ◽

M. Knight ◽

R. T. Jensen ◽

J. D. Gardner

Keyword(s):

Guinea Pig ◽

Partial Agonist ◽

Effective Concentration ◽

Amylase Secretion ◽

Agonist Activity ◽

Pancreatic Acini ◽

Rat Pancreas ◽

Partial Agonist Activity ◽

Stimulation Of

In dispersed acini from guinea pig pancreas, cholecystokinin-(27-32)-amide [CCK-(27-32)-NH2] did not stimulate amylase secretion and inhibited the stimulation caused by CCK-(26-33). In dispersed acini from mouse or rat pancreas, CCK-(27-32)-NH2 stimulated amylase secretion. The stimulation of amylase secretion caused by a maximally effective concentration of CCK-(27-32)-NH2 was less than that caused by a maximally effective concentration of cholecystokinin-(26-33), and in contrast to the action of cholecystokinin-(26-33) supramaximal concentrations of CCK-(27-32)-NH2 did not cause submaximal stimulation of amylase secretion. Dibutyryl cGMP and proglumide each inhibited the stimulation of amylase secretion caused by CCK-(27-32)-NH2. CCK-(27-32)-NH2 inhibited binding of 125I-labeled CCK to mouse and rat pancreatic acini. These results indicate that, in mouse and rat pancreatic acini, CCK-(27-32)-NH2 is a partial agonist and that this partial agonist activity is produced by occupation of the CCK receptor by CCK-(27-32)-NH2.

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Ultrastructural analysis of the spermatogenesis in the guinea pig (Cavia porcellus)

Pesquisa Veterinária Brasileira ◽

10.1590/s0100-736x2016001300013 ◽

2016 ◽

Vol 36 (suppl 1) ◽

pp. 89-94 ◽

Cited By ~ 1

Author(s):

Luciana S. Simões ◽

Rose E.G. Rici ◽

Phelipe O. Favaron ◽

Taís Harumi de Castro Sasahara ◽

Rodrigo S.N. Barreto ◽

...

Keyword(s):

Electron Microscopy ◽

Guinea Pig ◽

Sexual Development ◽

Morphological Changes ◽

Light And Electron Microscopy ◽

Management Systems ◽

Cavia Porcellus ◽

Reproductive Parameters ◽

Development Stages ◽

Transmission Electron

Abstract: al for both, the establishment of appropriate management systems, and for the use of new species as animal models. In this study, we used light and electron microscopy to characterize the sexual development stages of the guinea pig (Cavia porcellus) in specimens of 30, 45 and 90 days of age. We observed the differentiation of spermatocytes only through transmission electron microscopy in the leptotene, zygotene and pachytene phases of meiosis, in 30-day-old animals. During puberty, there was differentiation of the germinative epithelium and formation of the acrosome. Spermatozoa, however, were not detected. Thus, we could infer that puberty happens after 45 days of age. Sexual maturity was evident in 90-day-old specimens. Our results showed that changes in the testicular germinative epithelium during the postnatal sexual development in guinea pig led to morphological changes, including the ones related to the development of Leydig and Sertoli cells, which are directly related to puberty. In this work, we provide new morphological subsidies for a better understanding of reproductive parameters of this species, enabling its use as an animal model in the field of the reproductive biology.

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Ultrastructural changes of endothelium associated with thrombocytopenia

Blood ◽

10.1182/blood.v46.4.567.567 ◽

1975 ◽

Vol 46 (4) ◽

pp. 567-578 ◽

Cited By ~ 87

Author(s):

CS Kitchens ◽

L Weiss

Keyword(s):

Electron Microscopy ◽

Endothelial Cells ◽

Guinea Pig ◽

Adult Male ◽

Ultrastructural Changes ◽

Endothelial Surface ◽

Endothelial Junctions ◽

The Relationship

Abstract In a study of the relationship between thrombocytopenia and increased vascular fragility, changes in the endothelium of capillaries and postcapillary venules of the tongue were examined by electron microscopy. Adult male albino rabbits (4 kg) were maintained thrombocytopenic (platelets less than 20,000/cu mm) up to 24 hr by one to three injections of guinea pig antirabbit platelet serum. Within 6 hr the normal projections and folds of the lumenal surface of the endothelial surface were largely effaced. In addition, the endothelium became thinner. In places, pores and membranous diaphragms were observed. Endothelial junctions appeared normal. Identical findings were observed if rabbits were made thrombocytopenic by administration of intraperitoneal busulfan. Intravenously administered Thorotrast was observed in endothelial cells and in the extravascular spaces within 3 min after injection into thrombocytopenic animals, while it was seen only intravascularly in control rabbits. With the spontaneous restoration of circulating platelets, the endothelium reverted to normal.

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